Probucol, introduced relatively recently as an antihypercholesteremic drug, differs chemically from other drugs. Chemically, probucol is orifto-di-ieributyl substituted to-mercap-tophenol. The mechanism of action of probucol is unknown. Being a lipophilic compound, it is easily distributed into fatty tissue and, as a result, approximately 20% of its maximum concentration in the blood is still maintained for 6 months.
Probucol reduces the overall level of cholesterol—primarily low-density lipoproteins— without having an effect on triglycerides and very low-density lipoproteins. It has been suggested that it inhibits synthesis of cholesterol itself and increases removal of bile salts. Upon using this drug, a fraction of low-density proteins is reduced; however, even more significant is the reduction of high-density proteins. From the epidemiological point of view, this is dangerous, because lowering the concentration of high-density proteins means less cholesterol is removed from tissues. However, in any case, probucol lowers the level of cholesterol in the plasma by 10-15%. Moreover, it has been shown that probucol facilitates reduction of necrotic zones in myocardial ischemia. It is used for problems with lipid exchange associated with an elevated level of cholesterol and low-density lipoproteins when diet and physical exertion do not have a sufficient hypocholesterinemic effect. Synonyms of this drug are bifenabid and lorelco.
Lovastatin and mevastatin: Lovastatin, (1S,3R,7S,8S,8aR)-1,2,3,7,8,8a-hexahydro-3, 7-dimethyl-8-[-[2R,4R]-[tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl]ethyl]-1-naphthyl (S)-2-methylbutyrate (20.2.7) is isolated from Monascus rubber  and Aspergillus terreus , as is mevastatin (1S,3R,7S,8S,8aR)-1,2,3,7,8, 8a-hexahydro-7-methyl-8-[-(2R,4R)-[tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl]ethyl]-1-naphthyl (S)-2-methylbutyrate (20.2.8), which is isolated from Penicillium citrinum [19, 20] as well as from Penicillium brevicom-pactum .
Lovastatin and mevastatin are new-generation drugs that were introduced into medicine for treating hyperlipocholesterolemia, and they are unique compounds. Lovastatin is isolated from Aspergillus terreus mushrooms. Mevastatin is a chemically analogous compound that differs only in the absence of a methyl group at C3 of the naphthaline system, and it is isolated from Penicillium citrinum mushrooms.
These hypolipidemic agents are noncompetitive inhibitors of the enzyme that limit the rate of cholesterol synthesis in the liver at the levalonic acid stage.
It is considered the most effective drug for lowering levels of cholesterol, triglycerides, and very low-density lipoproteins in the plasma and for moderately increasing the number of high-density lipoproteins. It is used for treating hyperlipoproteinemia that cannot be corrected by a special diet or physical exertion. Synonyms of lovastatin are lovalip, meva-cor, mevinacor, and sivlor; and those of mevastatin are CS-500 and ML-236 B.
Nicotinic acid: Nicotinic acid, pyridine-3-carboxylic acid (20.2.9) is synthesized industrially by heating a paraldehyde trimer of acetaldehyde, under pressure with ammonia, which leads to the formation of 2-methyl-5-ethylpyridine, followed by oxidation with nitric acid which gives the desired product [22-25].
In large doses, nicotinic acid, or vitamin B3 or vitamin PP, lowers the levels of both cholesterol and triglycerides in the plasma. Despite the fact that it has extremely problematic side effects, it has a long and successful history as an antihyperlipoproteinemic drug. However, it is not taken as a vitamin. Its action is connected with a reduction of very low-density protein production, which evidently is linked to inhibition of lipolysis in fatty tissue. It is important to notice that nicotinic acid does not have an effect on the general synthesis of cholesterol in the organism. Nicotinic acid or nicotinic acid in combination with bile acid-reducing drugs can lower the level of cholesterol and triglycerides by
Was this article helpful?